1. Field of the Invention
This invention relates to surgery and orthopaedic instrumentation. More particularly, this invention relates to a talonavicular joint prosthesis and the surgical procedure and apparatus for its implantation.
2. Description of the Related Art
The talonavicular joint is comprised of the articulation between the talus and navicular bones. For many years, one of the more aggressive methods for treating diseased or injured talonavicular joints was a fusion between the talus and navicular bones. Unfortunately, this method has had significant drawbacks—e.g., hindfoot motion is greatly reduced; limiting the motion in the joint results in greater load distribution in adjacent joints—which can yield further degenerative disease. Other widely used treatments have included orthotics, braces, physical therapy and cortisone shots.
More recently, considerable interest has developed in the use of joint replacement methods and equipment (e.g., an artificial joint, called a prosthesis) to treat diseased or injured joints in the foot and ankle. Such methods entail the degenerative articular surfaces of the joint being removed and replaced with a prosthesis.
Among the joints attempted to be treated by joint replacement methods is the talonavicular joint, see U.S. Pat. No. 3,965,489. The prosthesis disclosed in U.S. Pat. No. 3,965,489 consists of disc-shaped talar and navicular components that have interfacing bearing surfaces with complimentary concave and convex curvatures. On the back sides of these surfaces are tapered ribs which are fitted into slots that are surgically created in the talus and navicular bones to which these components are affixed. This prosthesis involves the surgeon utilizing a dorsal approach to the joint and primarily flat cuts across the joint space. Such a surgical approach and the size of the prosthesis' components results in the resection of an inordinate amount of bone and the compromising of adjoining critical bony and soft tissue structures. This situation has reportedly led to the diminishment over time of the stability of the orientation of the prosthesis' components and the ultimate failure of the prosthesis.
There exists a need for the development of an improved talonavicular joint prosthesis that will better follow the natural anatomic contours of the joint space while preserving critical portions of the distal talus and proximal navicular bone surfaces to which it is affixed.
3. Objects and Advantages
There has been summarized above, rather broadly, the prior art that is related to the present invention in order that the context of the present invention may be better understood and appreciated. In this regard, it is instructive to also consider the objects and advantages of the present invention.
It is an object of the present invention to provide an improved talonavicular joint prosthesis for the replacement of the arthritic, deformed, or degenerated talonavicular joint articulation and thereby eliminate the need for talonavicular joint fusion.
It is another object of the present invention to provide a less invasive surgical method for preparing the joint space and inserting a talonavicular joint prosthesis to allow for the preservation of the critical portions of the distal talus and proximal navicular and the better retention and stable attachment of the joint's essential soft tissue structures.
It is another object of the present invention to provide a talonavicular joint prosthesis and its surgical method of implantation that will yield improved patient healing and a decrease in the failure rate of such devices.
It is a further object of the present invention to provide a talonavicular joint prosthesis and its surgical method of implantation that utilizes a precision cutting tool and fixation jig apparatus to prepare the talonavicular joint for the insertion of the prosthesis, wherein this tool and apparatus allow for minimum bone resection by allowing the surgeon to follow the natural contours of the talonavicular joint so as to preserve the strongest portion of the distal talus and proximal navicular for implantation of the talonavicular prosthesis.
It is an object of the present invention to provide a more mechanically sound talonavicular joint prosthesis which is also more conducive to biologic incorporation into a patient's body.
It is also an object of the present invention to provide a talonavicular joint prosthesis which is more mechanically and biologically compatible with arthroplasty of adjacent joints in the foot and ankle.
It is an object of the present invention to provide a talonavicular joint prosthesis and its surgical method of implantation that utilizes a precision cutting tool and fixation jig apparatus which will allow a surgeon to cut forwards and backwards in the patient's new joint space that is created for the prosthesis.
These and other objects and advantages of the present invention will become readily apparent as the invention is better understood by reference to the accompanying summary, drawings and the detailed description that follows.